There are many commercial processes in which separation of one or more materials is achieved by the general technique of: (1) first contacting a fluid mixture with an adsorbent in an adsorbent zone to selectively adsorb one or more materials of the mixture by the adsorbent material, thereby effecting a separation of the mixture components; and (2) subsequently desorbing the adsorbent material by either (a) reducing the total pressure of the bed and then purging the bed at low pressures (pressure swing processes), (b) purging the bed at operating pressures by treating the adsorbent material with an elutant material which has its temperature raised to a point sufficient to promote desorption of the adsorbent material (thermal swing processes), and (c) by purging the bed with an elutant material which displaces the previously adsorbed material, the elutant itself being adsorbed by the adsorbent (displacement desorption processes). Stated differently, in cyclic adsorption processes partition of an adsorbable component between an absorbent and a fluid mixture is achieved by successive adjustment of process conditions promoting adsorption and desorption respectively.
In processes of the above type, the adsorption reaction is virtually always an exothermic reaction and the heat of adsorption generally is removed from the adsorbent zone as sensible heat in the effluent gas. Commonly, the heat of adsorption is wasted, and if utilized, it is not utilized efficiently. Additionally, in thermal swing cyclic adsorption processes, heat is provided in order to desorb the adsorbed material. Failure to efficiently utilize the heat of adsorption as well as requiring inputting thermal energy to achieve satisfactory desorption renders thermal cyclic adsorption processes less energy efficient than is desired. The present invention is directed toward improving the thermal efficiency of cyclic adsorption processes.